1. Field of the Invention
The present invention relates to a voice data communication system (i.e., Internet telephone system) using an Internet protocol (IP) network, and more particularly, to an Internet telephone system capable of ensuring the quality of voice data communication (communication quality or QoS (Quality of Service)) and a path setting method.
2. Description of the Related Art
In recent years, there have been experiments to implement interactive communication through a telephone by using a network adopting an Internet protocol (in particular, Internet), and an ITU-T recommendation on a VoIP (Voice over Internet Protocol) has been issued. Also, RFCs (Request for Comments) have also been issued from an IETF (Internet Engineering Task Force). For example, the IP, voice converting method (RTP), communication system (MGCP: Media Gateway Control Protocol) are described in the IETF RFC760, IETF RFC1889, and IETF RFC2705, respectively.
However, the IP allows the delay in transfer of a packet and the disposition of the packet which are caused by congestion and, therefore, the IP is not suitable to real-time interactive communication. The ITU-T recommendation prescribes a method for solving a problem of the conversion between a telephone number and an IP address and a method for converting (mapping) voice data into an IP packet and, however, it prescribes no method for ensuring communication quality. The IETF proposes only a schematic standard for Internet telephone system.
Accordingly, predetermined communication quality must be ensured by preventing the disposition of a voice packet on the IP network and by reducing the delay in transfer of the packet to realize the Internet telephone system to satisfy user's desire.